Safety control for oil burners



Sept. 19, 1939. R. F. ANDLER 2,173,465

SAFETY CONTROL FOR OIL BURNERS Filed Dec. 23, 1937 ATTORNEY.

Patented Sept. 19, 1939 UNITED STATES PATENT OFFlCE Robert F. Andler, Rutherford, N. 3., assignor to Electrol Incorporated, Clifton, N. J a corporation of Delaware Application December 23, 1937, Serial No. 181,300

4 Claims.

My invention relates to oil burners and more specifically to apparatus to control, prevent, or stop the oil feed in the event of the failure of the ignition. It is well known in the industry that 5 when the oil burner is started, should the gap between the ignition points be too wide to establish a spark, or should the gap be closed by carbon, or should a short circuit occur in any part of the lines, a continuation of the supply of fuel oil might have disastrous results when a spark is finally established. For example, controls have been built whereby when suitable primary voltage exists across an ignition transformer, a relay is closed which starts the oil flow. This system is unsatisfactory because the secondary of an igni tion transformer could be defective and still the oil would continue to flow. Other control systems have been devised whereby a flow of current in the primary side of a transformer will cause the oil to flow. This is not satisfactory because if the electrodes were dead-shorted by any cause, oil would be admitted into the combustion area. Other systems have been devised whereby actual flow of current in the secondary or high tension side of the transformer operates the relay, which in turn permits the oil to flow. This is unsatisfactory because of the difficulty of insulating the high tension current and also because shorted electrodes would still cause the oil fuel to flow. Another device causes the relay to close the circuit to the oil fuel supply means whenever a flux exists on the core .of an ignition transformer. This is defective because short circuited electrodes would still cause the admission of oil into a possibly hot combustion chamber. All these control systems are objectionable because they were not based on having correct conditions established before starting the oil supply means.

The foregoing facts lead to the conclusion that complete safety can only be obtained by constructing apparatus where the oil supply means cannot be started until and unless correct ignition conditions are present.

My invention has for its object to provide a construction which will overcome all of the foregoing objections and which will provide a structure which will not operate or be operative unless and until correct ignition conditions are present.

A further object is to so construct the control that when such proper conditions are not present the current will be cut off and the oil supply means be inoperative. In order to accomplish this, I utilize the voltage-current conditions of the primary circuit of the ignition transformer which I have determined are always in a certain relationship when correct ignition conditions exist. Inasmuch as this varies Widely from open circuit conditions on either a primary or secondary, or short circuit conditions of the secondary and correct conditions when a proper spark is 5 established, I employ a means for making and breaking the circuit to the oil flow means such as a relay which may be constructed of a design similar to the conventional wattmet'er or powerfactor meter the construction of which is. well 10 known.

As the volt-ampere relationship in the primary circuit varies with differences in condition of both the primary and secondary circuits between correct and incorrect ignition conditions, the change 15 in magnetic flux Works to close or open a switch in the circuit to the oil supply means. When anything occurs which prevents the ignition from operating, it will be clear that the switch can be so arranged that the failure of flow of the second- 1 ary current, shorting of the secondary circuit, or an improper condition of the arc will automatically open such switch and stop or prevent the operation of the oil flow means. If a spark is established the volt-ampere relationship in the 25 primary circuit of the transformer will immediately become such as to close the switch and permit the burner to function. The establishing of correct conditions to determine either an open or closed switch position for controlling the oil 30 fuel supply means, is of course optional, depending on the type of apparatus employed. Thus I am sure of having proper ignition conditions before oil could ever be admitted into the combustion area.

My means of accomplishing the foregoing objects may be more fully comprehended by having reference to the accompanying drawing which is hereunto annexed, and is a part of this specification in which:

The figure is a more or less diagrammatic view of an oil burning system equipped with my control.

Similar reference numerals refer to similar parts throughout the entire specification.

As shown in the drawing, I have illustrated relay 1 diagrammatically, constructed similarly to a watt-meter of the moving coil type, the principle of which is so well known as to obviate the necessity of any detailed description. The 50 relay is provided with a switch arm 2 which can if desired be used to indicate the condition of the equipment, or in other words, to indicate a function of the power conditions of the circuit. This switch arm 2 carries a contact 3 adapted to register with a pair of spaced contacts 4 and 5 so as to close the gap between the two contacts 4 and 5 when the switch arm 2 is moved by the magnetic flux in the relay until it reaches the condition where the switch arm 2 will cause the contact carried by it to close the gap between contact points 4 and 5, thus permitting the current to flow through the conductors to the motor M. It may be desirable in some circumstances to employ an adjustable contact point support 6 instead of having it fixed. In such a case the support may be fastened in place with a screw I mounted in a slot 8 which permits shifting it to any desired position.

From the foregoing it will be clear that as long as the volt-ampere condition through the primary of the transformer T is due to a spark or arc at the electrodes E the relay will hold the switch closed and the current will flow to the motor M and the oil fuel supply means P will operate but if for any of the reasons such as referred to above, the magnetic flux is lessened, it need not be completely stopped, the switch arm 2 will move away from the contact points 4 and 5 and the current will be cut off, thus stopping the operation of the oil fuel supply means.

It will be obvious to persons skilled in the art that my invention is not limited to any specific structure but so long as the closing and opening of the contacts is brought about by the presence or absence of correct ignition conditions it will be within the scope of my invention as claimed.

Having described my invention, what I regard as new and desire to secure by Letters Patent is:

1. In a fluid fuel burner having electric ignition means, an electrical supply circuit for said electric ignition means, a fuel control means, said control means comprising a wattmeter connected in said circuit, a switch arm actuated thereby, a motor, electrical conductors leading thereto, a pair of spaced contacts for said conductors adapted to be opened or closed by the movement of said switch arm produced by the variation in the amount of power affecting said wattmeter.

2. In a fluid fuel burner having electric ignition means, an electrical supply circuit for said electric ignition means, a fuel control means, said control means comprising a wattmeter connected in said circuit, a switch arm actuated thereby, a motor, electrical conductors leading thereto, a pair of spaced contacts for said conductors adapted to be opened or closed by the movement of said switch arm produced by the variation in the amount of power affecting said wattmeter, means to adjust the point at which said contacts will be opened or closed by the contact carried by said arm.

3. In a fluid fuel burner having electric ignition means, the combination of an alternating current electrical supply circuit for said electric ignition means including a low voltage primary circuit, a transformer, and a high voltage secondary circuit; and a relay located in said primary circuit having a coil responsive to voltage conditions therein and a second coil responsive to current conditions therein, said relay controlling the supply of fuel to said burner, whereby fuel may be supplied to said burner only when the wattage in said primary circuit lies within a predetermined range of values.

4. In a fluid fuel burner having electric ignition means, the combination of an alternating current electrical supply circuit for said electric ignition means including a low voltage primary circuit, a transformer, and a high voltage secondary circuit; and a relay located in said pri mary circuit having a coil responsive to voltage conditions therein and a second coil responsive to current conditions therein, said relay controlling the supply of fuel to said burner, whereby fuel may be supplied to said burner only when the wattage in said primary circuit exceeds a predetermined value.

ROBERT F. ANDLER. 

